Question

scientific method - controls and variables
definition of key terms
control - a part of the experiment that is not being tested and is used for comparison.
variable - any part of an experiment that can change.
independent variable - the part of the experiment that is changed by the scientists or person performing the experiment.
dependent variable - the part of the experiment that is affected by the independent variable.
spongebob and his pals have been busy doing a little research. read the description for each experiment and answer the questions.
krusty krabs breath mints
mr. krabs created a secret ingredient for a breath mint that he thinks will “cure” the bad breath people get from eating crabby patties at the krusty krab. he asked 100 customers with a history of bad breath to try his new breath mint. he had fifty customers (group a) eat a breath mint after they finished eating a crabby patty. the other fifty (group b) also received a breath mint after they finished the sandwich; however, it was just a regular breath mint and did not have the secret ingredient. both groups were told that they were getting the breath mint that would cure their bad breath. two hours after eating the crabby patties, thirty customers in group a and ten customers in group b reported having better breath than they normally had after eating crabby patties.

1. which people are in the control group?

a. group a
b. group b

1. what is the variable?

a. the actual breath mint.
b. the crabby patties.
c. the secret ingredient in the breath mint.
d. how many crabby patties eaten.

1. what should mr. krabs’ conclusion be?

a. the breath mint with the secret ingredient does reduce breath odor.
b. the breath mint with the secret ingredient reduces breath odor over 50% of the time.
c. the breath works, but it is not 100% effective.
d. all of the above.
spongebob clean pants
spongebob noticed that his favorite pants were not as clean as they used to be. his friend sandy told him that he should try using clean - o detergent, a new laundry soap she found at sail - mart. spongebob made sure to wash one pair of pants in plain water and another pair in water with the clean - o detergent. after washing both pairs of pants a total of three times, the pants washed in the clean - o detergent did not appear to be any cleaner than the pants washed in plain water.

1. what was the problem spongebob wanted to investigate?

a. is clean - o detergent effective?
b. is the length of time the pants are washed important?
c. how does water temperature affect cleaning pants?
d. does how often i wash my pants affect how clean they are?

1. what is the variable?

a. water temperature.
c. laundry soap

Explanation:

1. The control group is the one not getting the treatment being tested. Group B has a regular breath - mint, so they are the control group.
2. The variable is what is changed between the groups. Here, it's the secret ingredient in the breath - mint.
3. 30 out of 50 in Group A and 10 out of 50 in Group B reported better breath. So the mint with the secret ingredient reduces breath odor more often than the regular one, but not always. All the statements in option d are correct.
4. SpongeBob wants to know if the new Clean - O detergent works, so that's the problem he's investigating.
5. He changes the type of laundry soap (plain water vs Clean - O detergent), so the variable is the laundry soap.

Answer:

1. b. Group B
2. c. The secret ingredient in the breath mint.
3. d. All of the above.
4. a. Is Clean - O detergent effective?
5. c. Laundry soap